A content delivery network (Content Delivery Network, CDN for short) is a network established based on the existing Internet. A content provider (Content Provider, CP for short), based on a CDN, publishes content to a network “edge” closest to a user, so that the user may obtain the desired content nearby, so as to alleviate congestion in a backbone network and improve a response speed. In an actual application, based on factors such as accounting management, a CP is often inclined to subscribe to one CDN service provider rather than subscribe to multiple CDN service providers. Network coverage of any single CDN service provider is limited, but users are scattered in different regions around the world. Therefore, interconnection and interworking need to be achieved between networks of different CDN service providers, so as to share the networks to achieve wider coverage, thereby delivering, to more end users, content of a CP that subscribes to the CDN service providers more end users.
In order to achieve CDN interconnection and interworking, CDNs deployed in different regions by a CDN service provider are interconnected to each other through the Internet to form a CDN interconnection system. In the CDN interconnection system, there is usually a plurality of CDNs capable of providing a service for a same user, interconnection and interworking are achieved between the CDNs; a CDN, closer to a same user for which the CDN is capable of providing a service, for example a user A, is called a downstream CDN (Downstream CDN, DCDN for short), and a CDN farther from the user A is called an upstream CDN (Upstream CDN, UCDN for short). When an upstream CDN receives a user request, the upstream CDN directly forwards the user request to a downstream CDN close to the user. If the downstream CDN cannot provide a service for the user request forwarded by the upstream CDN, the upstream CDN forwards the user request to another downstream CDN close to the user; attempts are made in this way repeatedly, so that the user can obtain a desired content nearby.
In the prior art, when performing a route decision on a to-be-forwarded user request, an upstream CDN determines, through repeated attempts, a downstream CDN that actually can push content to a user, and therefore, the route decision efficiency is low.